linux-kernel - Re: [PATCH] iommu: replace single-char identifiers in macros

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Message-ID: <fe5e8da4-38d2-c663-c2e2-70e6d4f7640f@arm.com>
Date:   Mon, 3 Jun 2019 14:07:38 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     Qian Cai <cai@....pw>, jroedel@...e.de
Cc:     akpm@...ux-foundation.org, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iommu: replace single-char identifiers in macros

On 03/06/2019 13:59, Qian Cai wrote:
> There are a few macros in IOMMU have single-char identifiers make the
> code hard to read and debug. Replace them with meaningful names.
> 
> Suggested-by: Andrew Morton <akpm@...ux-foundation.org>
> Signed-off-by: Qian Cai <cai@....pw>
> ---
>   include/linux/dmar.h | 14 ++++++++------
>   1 file changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/include/linux/dmar.h b/include/linux/dmar.h
> index f8af1d770520..eb634912f475 100644
> --- a/include/linux/dmar.h
> +++ b/include/linux/dmar.h
> @@ -104,12 +104,14 @@ static inline bool dmar_rcu_check(void)
>   
>   #define	dmar_rcu_dereference(p)	rcu_dereference_check((p), dmar_rcu_check())
>   
> -#define	for_each_dev_scope(a, c, p, d)	\
> -	for ((p) = 0; ((d) = (p) < (c) ? dmar_rcu_dereference((a)[(p)].dev) : \
> -			NULL, (p) < (c)); (p)++)
> -
> -#define	for_each_active_dev_scope(a, c, p, d)	\
> -	for_each_dev_scope((a), (c), (p), (d))	if (!(d)) { continue; } else
> +#define for_each_dev_scope(devs, cnt, i, tmp)				\
> +	for ((i) = 0; ((tmp) = (i) < (cnt) ?				\

Given that "tmp" actually appears to be some sort of device cursor, I'm 
not sure that that naming really achieves the stated goal of clarity :/

Robin.

> +	    dmar_rcu_dereference((devs)[(i)].dev) : NULL, (i) < (cnt)); \
> +	    (i)++)
> +
> +#define for_each_active_dev_scope(devs, cnt, i, tmp)			\
> +	for_each_dev_scope((devs), (cnt), (i), (tmp))			\
> +		if (!(tmp)) { continue; } else
>   
>   extern int dmar_table_init(void);
>   extern int dmar_dev_scope_init(void);
>